NET, IAS, State-SET (KSET, WBSET, MPSET, etc.), GATE, CUET, Olympiads etc.: Physics MCQs (Practice_Test 29 of 35)
Doorsteptutor material for competitive exams is prepared by world's top subject experts: get questions, notes, tests, video lectures and more- for all subjects of your exam.
- A plan em wave E2 = 100 cos (6 × 108t + 4x) V⟋m propagates in a medium of dielectric constant
- 1.5
- 2.0
- 2.4
- 4.0
- In a mass spectrometer, the velocity filter employs electric field E and a perpendicular magnetic field B. The deflecting magnetic field perpendicular to the. Beam is ‘B’ Ions with similar charges ‘q’ and mass numbers m1 and m2 pass through the filter. After a 180 turn in the deflecting field, the separation between them will be
- E (m2 − m1) ⟋q B B ′
- 2E (m2 − m1) ⟋q B B ′
- Fq (m2 − m1) ⟋BB ′
- 2Eq (m2 − m1) B B ′
- The emf of a thermocouple, one junction of which is at 0 degree C is given by E = at + bt2 The Peltier coefficient is given by (T is in Kelvin)
- T 2at + b
- T 2a + bt
- T a + bt
- T a + 2bt
- A cyclotron having segments of radius 50 cm is used for accelerating hydrogen nuclei. The polarity of the segments is reversed 5 × 107 times per second. The energy of the incoming proton beam is (mass of the proton = 1.673 × 10 − 24 gm, 1.6 × 10 − 12 erg = l e V)
- 3.225 MeV
- 32.25 Me V
- 3225 MeV
- 0.3225 Me V
- A copper disc of 10 cm radius makes 1200 revolutions per minute with its plane perpendicular to a magnetic field, If the induced emf between the centre and edge of the disc is 6.28 millivolt, then the intensity of the field is
- 100 Oersted
- 80 Oersted
- 60 Oersted
- 50 Oersted
- An election (mass = me) and a proton (mass = 1836 me) are moving with the same speed. The ratio of their deBroglie wavelengths l electron⟋l proton will be
- 1
- 1836
- 1⧵1836
- 918
- A hydrogen-like atom a has a p-meson of mass 200 times that of an electron, bound to the proton. The radius of the first Bohr orbit of this moronic atom will be
- equal to that of H
- 10 times that of H
- 200 times that of H
- times that of H
- The frequency of the Ka line of characteristic X-ray spectrum is proportional of (Z = atomic number)
- Z
- Z
- Z2
- Z
- The wavelength of the photoelectric threshold for silver is lo. The energy of the electron elected from the surface of silver by an incident light of wavelength l l (< lo) will be
- hC (l0 − l)
- hC⟋l0 l-
- h⟋C (1⟋l l⟋1 − 0)
- hC (l0 l) l − 0l
- Consider the following statements.In Compton scattering, the shift in the wavelength of the incident photon depends upon the
- wavelength of the incident photon.
- nature of the scattering substance.
- angle of scattering.
- Of these statements
- 1 and 2 are correct
- 1 and 3 are correct
- 3 alone is correct
- 2 and 3 are correct
- If 20% of a radioactive isotope decays in 5 days, then the amount of the original material left after 15 days will be approximately
- 20%
- 50%
- 60%
- none of the above
- If the mass of a particle is three times its rest mass, then the speed at which the particle is moving is (C = velocity of light)
- C
- C
- C
- 3C
- Which one of the following is a set of Magic Numbers?
- 1, 2, 8,16, 20,28
- 2, 8, 16,20, 28,50
- 8, 28, 50, 82,100, 126
- 2, 8, 20, 28, 50,82, 126
- The average binding energy per nucleon is 7.6 Me V for a heavy nucleous such as uranium while it is 8.5 Me V for nuclei with mass numbers around 110. The energy released in binary fission of U − 235 by slow neutrons will be approximately
- 7.6 MeV
- 8.5 MeV
- 212.4 MeV
- 235 MeV
- The beta decay of the neutron is explicitly given by
- n-p + e
- n-p + e + ue
- n-p + e + ue
- n-p + e + g